Question: A jar contains $6$ red marbles, $4$ green marbles, and $10$ blue marbles. If a marble is randomly chosen, what is the probability that it is green?
Answer: There are $6 + 4 + 10 = 20$ marbles in the jar. There are $4$ green marbles. The probability is $ \frac{4}{20} = \dfrac{1}{5}$.